USP Spectrum Expansion System

The following article was taken from Sinclair User - October 1983

ZX Spectrum Expansion. . . . Starts with one card . . . . . Extend up to seven cards !

The price/computer power ratio of the Spectrum is tremendous but up to now it's lacked one major thing compared with other Z80, 48k computers costing many times more - expandability.
U-Microcomputers have been the UK leaders in Apple Expansion cards, but with the Spectrum we've had to provide the means to expansion (3 and 4 slot backplanes) as well as the initial range:

USP-ADAP - £6.90
A back to back adaptor needed when you buy your first card and later for the backplane.

USP-BBP3 - £35.65
A buffered 3 slot back plane, meaning it won't interfere with the Spectrums operation. It will generally require an auxilary power supply either home built or the USP-Power supply unit (available later). A side connector allows use of the ZX Printer and Microdrives.

USP-BPE4 - £25.30
Provides a further four slots after you have the USP-BBP3

USP-PROT - £18.30
Prototyping card - use to design and test your own circuits.

USP-232D - £34.50
Dual channel serial RS232 interface using the sophisticated and very powerful Z80DART chip. Includes LPRINT and LLIST patches and a terminal emulator program. Baud rate 75-9600, full handshaking available.

USP-I/O - £29.90
General purpose parallel interface using versatile Z80PIO chip. Use to connect to parallel printers, music synthesisers, plotters, D-to-A and A-to-D converters, relays, LED's. . . It provides two 8 bit input or output ports with 4 handshaking lines.

USP-CENT - £3.45
A kit for use with the USP-I/O for centronics compatible printers.